On Fri, 9 Feb 2001, Jun Sun wrote:
> a) an explicit config option, CONFIG_HAS_FPU, (which is not associated with
> PrID), plus "#ifdef CONFIG_HAS_FPU ..." code. Or
>
> b) have run-time detection and many "if .. then .." code.
>
> I listed some pro's and con's for both of them in my first email. Right now,
> I found myself not having a strong preference but still biased towards config
> option approach ( - as if that really matters. :-0)
Well, the number of places a run-time condition exist is small and they
are not performance-critical.
> I actually don't understand your IDT quote. It requires one to call mfc1 to
> get FCR0. On many CPUs without a FPU, this will generate an exception. Are
> you suggesting that we should catch the exception and from that we conclude
> there is no FPU present?
I don't have an FPU-less system and I can't check such code. I need to
depend on others (I couldn't test all possible configurations anyway). If
we have a chance to get an exception we have to catch it, of course
(that's trivial to handle in Linux).
--
+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+--------------------------------------------------------------+
+ e-mail: macro@ds2.pg.gda.pl, PGP key available +